ANDROID: Use DTC from PATH. (2nd attempt)

This is a re-apply of 2a2cffe
("ANDROID: Use DTC from PATH.") that adds DTC from PATH. Because
checkpatch.sh and checkpatch_presubmit.sh no longer exists, and it is
not allowed to source _setup_env.sh directly, this change can be
re-applied.

The warning message has been there for a year now, so it is okay to
remove it so that, if dtc is not found in PATH, $DTC is left empty.

Below is the original message.

ANDROID: Use DTC from PATH.

Instead of using a hard-coded path to DTC, infer its
path from PATH. This change removes the dependency on
the ${BUILDTOOLS_PREBUILT_BIN}/dtc symlink, so the
build infrastructure is free to reset PATH to a place
where the actual DTC binary exists.

This change is needed to set
--incompatible_disable_hermetic_tools_symlink_source
to true by default.

Test: bazel run //common:db845c_dist
Fixes: a71e480 ("ANDROID: build.config: Set DTC to absolute path")
Bug: 291816237
Change-Id: I4f6051dc079a33c8e5e2632aa7ed040049300601
Signed-off-by: HONG Yifan <[email protected]>

Author: HONG Yifan

build.config.common

@@ -3,12 +3,7 @@
 BRANCH=android-mainline
 LLVM=1
 DEPMOD=depmod
-
-# TODO(b/296265825): Turn this into a proper error
-DTC=$(command -v dtc || { echo "WARNING: $BUILD_CONFIG loaded without Kleaf hermetic tools.
-    This will become an error in the future." >&2;
-    echo "${ROOT_DIR}/${BUILDTOOLS_PREBUILT_BIN}/dtc";
-})
+DTC=$(command -v dtc)
 
 KCFLAGS="${KCFLAGS} -D__ANDROID_COMMON_KERNEL__"
 EXTRA_CMDS=''